Soft and Chewy Monster Cookies
These monster cookies are made with my favorite peanut butter oatmeal cookie dough, and there are M&M’s and chocolate chips in every single bite. There’s no dough chilling required and you can use any mix-ins you like to customize your cookies!
*Originally published in July 2019. Post and pictures updated September 2026. *
After baking countless batches of these monster cookies over the years, I decided it was time to share the updated recipe I’ve been loving lately.
The peanut butter oatmeal cookie dough base is the same classic recipe that I first shared back in 2019, but this new and improved version calls for more chocolate chips (because you can never have too much chocolate!).
This is a no-frills cookie recipe that goes straight from the mixing bowl to the oven. The cookie dough doesn’t have to be chilled before being rolled into balls and baked, and you can use pretty much any combination of mix-ins you like.
It’s really the perfect “anytime” cookie recipe that’s ready in about 30 to 45 minutes. I love this easy recipe so much that I even included a variation of it in my cookbook!
Recipe Video
Ingredient Notes & Substitutions
Peanut Butter
Avoid natural peanut butter because it tends to separate and creates greasy cookies. A no-stir variety like Jif or Skippy is best.
Oats
I prefer using rolled oats to give these cookies a chewier texture. I’ve also tested this recipe with quick oats and they work great, so feel free to use whichever one you have on hand!
Mix-Ins
I used chocolate chips and M&M’s, but you can use your favorite baking chips, chopped pretzels, chopped nuts, etc. Mini M&M’s will work too!
Tips For Making These Cookies
- Mix the butter and sugar together long enough. Give it a good 1 to 2 minutes to properly cream together the sugar and butter. This incorporates the perfect amount of air into the butter so your cookies turn out soft and chewy, not cakey.
- Stop and scrape down the sides of the bowl often. You want all of the ingredients to be evenly incorporated into the dough.
- Measure your flour correctly. If you scoop the flour straight out of the bag with the measuring cup, you’re likely going to end up with too much and dry/crumbly cookies. Instead, you want to spoon it into the measuring cup, then level it off with the back of a butter knife. If you’re new to baking I have a full blog post explaining more about how to measure flour correctly.
- Use a cookie scoop. This will keep all of your cookies uniform in size. I love to use this 1.5-tablespoon cookie scoop for these monster cookies.
- Don’t over bake the cookies! My cookies usually take about 10 to 12 minutes. You’ll know they’re done when the tops are just set (no longer doughy) and the edges start to lightly brown. It’s also best to use a light colored baking sheet because it will bake the cookies more evenly. If you use a darker baking sheet, you may need to reduce the baking time slightly.
Can I Leave Out The Peanut Butter?
You can’t leave it out of this recipe without making adjustments to some of the other ingredients. If you want to make these cookies nut-free, you can replace the peanut butter with an equal amount of SunButter or Wowbutter.
Or you could use my oatmeal chocolate chip cookie recipe and just replace half of the chocolate chips with M&M’s.
Can I Bake This Recipe Into Bars?
Yes! This should be enough cookie dough for a 9-inch square pan, just bake until the top is set and lightly golden brown. If you’d prefer to make a larger batch in a 9×13 pan, you can use my monster cookie bar recipe instead.
Make a batch of these monster cookies this weekend and watch them disappear. I know you’re going to love them!
If you try this recipe, don’t forget to leave a comment and star rating below to tell me how your cookies turned out. Happy Baking!
Monster Cookie Recipe
Ingredients
- 1 cup all-purpose flour spooned & leveled (125 grams)
- 1 ¼ cups old-fashioned rolled oats (125 grams)
- ½ teaspoon baking soda
- ¼ teaspoon salt
- ½ cup unsalted butter softened (113 grams; 1 stick)
- ¾ cup packed light brown sugar (150 grams)
- ¼ cup granulated sugar (50 grams)
- ½ cup creamy peanut butter (125 grams; I recommend Jif or Skippy avoid natural pb)
- 1 large egg at room temperature
- 1 teaspoon pure vanilla extract
- ¾ cup M&M's (155 grams)
- ¾ cup semi-sweet chocolate chips (135 grams)
Instructions
- Preheat the oven to 350°F (177°C). Line two to three large baking sheets with parchment paper or silicone baking mats and set aside.
- In a large mixing bowl, whisk together the flour, old-fashioned rolled oats, baking soda, and salt. Set aside.1 cup all-purpose flour,1 ¼ cups old-fashioned rolled oats,½ teaspoon baking soda,¼ teaspoon salt
- In the bowl of a stand mixer fitted with the paddle attachment, or in a large mixing bowl using a handheld mixer, beat the butter, brown sugar, and granulated sugar together for about 1 to 2 minutes or until well combined. Mix in the peanut butter, egg, and vanilla extract until fully combined, making sure to stop and scrape down the sides of the bowl as needed.½ cup unsalted butter,¾ cup packed light brown sugar,¼ cup granulated sugar,½ cup creamy peanut butter,1 large egg,1 teaspoon pure vanilla extract
- Add the dry ingredients and mix until just combined. Add the M&M’s and chocolate chips and gently fold them into the cookie dough (you can also mix them in on low speed with your mixer).¾ cup M&M's,¾ cup semi-sweet chocolate chips
- Using a 1 ½ tablespoon cookie scoop, scoop the cookie dough onto the prepared baking sheets, making sure to leave a little room between each one.
- Bake in separate batches for 10 to 12 minutes or until the tops of the cookies are set and the edges are just lightly browned. Remove from the oven and allow to cool on the baking sheet for 5 to 10 minutes, then transfer to a wire rack to cool completely.
Made these today! Instant hit with my family. Will be adding to our favorite tried and true. They are so good! Thank you.
Wanted a monster cookie that was soft and chewy – not crispy – and a good balance of peanut butter and oats. This recipe is it! Even my anti-pb husband likes these! I get about 20 50gram cookies in a batch. These are going in my
Christmas treat box this year! Thanks for a 5 ⭐️ recipe
I have over 1500 tested cookie recipes in my collection and this is one of the best. The cookies are crispy around the edges and chewy in the centre. They’re a nice thickness and the flavours are well balanced. I doubled the vanilla but followed the recipe otherwise. I used the weight measures and my cookies look like the ones pictured, but bigger. My yield was 17, not 32. I let the dough rest at cool room temperature for about 2 hours before baking the cookies. Because they were bigger, the cookies took 13 minutes to bake. After testing so many recipes over the years it’s hard to find one that stands out, but this one definitely does.
Thanks for the recipe! I made a double batch of these and since the bulk was going to friends with a peanut allergy, I used tahini. They turned out perfectly and for those interested, you don’t taste the peanut butter, nut butter, tahini, etc. in the cookies. It’s all about that crunchy texture from the M&Ms and the perfect soft chewiness from the oatmeal cookie. Definitely a recipe I’d make again!
My cookies didn’t flatten out at all and were just like how they were when I scooped them??♀️ Other than that they tasted great and the recipe was super easy!
These are a hit, thanks! Made with mini chocolate chips and valentine m&ms and the whole family loves them! Great texture too, a perfect mix of the oats and flour.
I accidentally doubled the white sugar (was reading the PB line), and I threw in chopped walnuts that needed to be used up… when they came out of the oven, I really didn’t think they were going to firm up and hold their shape, but they did! After the first set, I formed them into patties with my hands (because – again – I thought they weren’t going to set, hahaha) which made me feel better, but all of them came out perfect despite my errors! And delicious! Thanks so much!
Perfectly chewy inside and crunchy edges. Such a delicious and easy recipe!
Danielle,
Your cookies are freaking incredible. These turn out every time. The peanut butter with the chocolate chips and m&m’s is like an explosion of flavors. I can also make these festive during holidays with seasonal m&ms. Thank you!!
Thank you, Shelly! I’m so glad you’re enjoying the cookie recipes!
I followed the recipe exactly and they turned out horribly. They were extremely dry and stayed in a ball. I had to flatten them down after ten minutes of baking. Very dissappointing.
Sorry you had trouble with the recipe, Mary. Did you make sure to spoon and level your flour or did you happen to scoop it from the container. Too much flour can lead to cookies that don’t flatten and turn out dry.
I was craving these so bad but only had maple and brown sugar instant oatmeal, I used 4 packets and lowered the amounts of the other sugars enough to compensate and I was out of chocolate chips, BUT!!! They still turned out so so so good!! Thank you for a great recipe! (Even though I had to tweak it at my own fault… lol)
Is it better to refrigerate the dough before baking?
For most of my cookies I recommend it, but I don’t find it necessary for this one.
Thank you! They came out great!!
Where is the nutrition?
I’m not sure about the nutritional information, but you can plug everything into an online calculator to get an estimate.
Hi there! Can we use crunchy peanut butter for this recipe? I wasn’t able to get my hands on creamy cause all the stores are empty!
Yes, that’s fine!
Hi there! Made these twice already. Once a normal batch, then a double one. My question, could i halve the sugar?thank you!!
You can cut down the sugar, but keep in mind that sugar helps cookies spread. If you reduce the sugar you may need to flatten the cookie dough before baking.
Hi! Your recipe looks good and simple to make. Can I use the same recipe to make bars instead of cookies?
Yes, absolutely! An 8-inch square pan may be a bit too small, an 11×7 or 9×13 pan may be better.
I followed the recipe exactly and still ended up with a crumbly mixture. What can I do to ensure that this won’t happen again? It was so crumbly, I could barely get them to form into a ball before baking.
Sorry you had trouble with the recipe, Caley. The cookie dough definitely shouldn’t be crumbly. Did you make any adjustments to the recipe and did you make sure to spoon and level your flour?
Do you need to use a paddle attachment?
It works best if you’re using a stand mixer, but the whisk attachment would work too.
These cookies sound amazing… I’m anxious to make them! I have some almond bark (for dipping) on hand… can I break it up and use it in these cookies? Or would it be too soft?
Thanks, Danielle, for all the great recipes.
Hi, Verna! Almond bark melts pretty easily, so I’m not sure that it would hold up well if you bake it in these cookies. I would suggest chocolate chips if you can use them.
Oh my goodness. These cookies are my family’s new favorite. I have made 10 batches in the last two weeks! And haven’t had one go to waste. I added peanut butter m&ms and only a handful of regular m&ms, along with milk chocolate chips. They turned out amazing. Definitely a new staple dessert. Thanks!
So happy to hear that, Dinah!
These cookies turned out perfectly! I baked 10 minutes and left on the pan for 6 or so. Perfectly soft with a little bit of crunch! So yummy. It made 25 cookies after some dough was eating by me and my munchkins! Nice recipe size so it doesnt go to waste and hopefully I dont eat a dozen! I didnt have enough MMs so I added vanilla chips til there was enough. Great chocolate to cookie distribution in the recipe! I put the MMs on top to make eyes and to reduce the puffiness. Super great recipe. It is bookmarked now.
Hi Danielle, can we replace egg with flax egg
I haven’t tried it, but I think it would be okay.
My eleven year old made these today with two of her girlfriends. She is an experienced baker, and she said they were easy to make and they tasted good. Mom sampled one too! Good stuff! Thanks for a solid, easy recipe. Looking forward to trying other ones from your blog now 🙂
So glad to hear that, Jamie! I’d love to hear if you try any other recipes!
Hi Danielle,
Thank you so much for a simple, delicious recipe! My cookies turned out super soft and yummy!
So happy to hear that, Michelle!
I have been searching for a good Monster cookie for a long time. I’ve tried a few others, but I always find them hard and dry. I am so thankful I found your recipe! They are DELICIOUS! My whole family loves them. I love how soft they are. Thank you!
Thank you, Ashley! So glad you and your family loved the cookies!
Can you use dalted butter
That would be fine, Sheila. I would reduce the salt in the recipe though and just use a pinch or maybe about 1/8 teaspoon instead.
Decided to make some monster cookies and this was the easier recipe. So far so good they in the oven and smelling awesome. I added a few extra m&ms and chocolate chips. Hope the little man likes them.
Hope you and your little one enjoy the cookies, Rebecca!
Can i freeze the dough for a week or two before baking?
Absolutely! You can scoop out the cookie dough into balls, place them on a baking sheet with parchment paper, and freeze them first (this helps to keep them from sticking together in a freezer bag/container). Then add the frozen balls of cookie dough to a freezer bag/container and store in the freezer until you’re ready to bake them. You can bake the cookie dough from frozen, just bake an additional 1-2 minutes if needed.
I made these this weekend for Valentine’s Day. I added the red, pink and white M&Ms to go with the holiday. They were a big hit! The old fashioned oats really do make a difference, my husband enjoyed the chewiness ? He joked and said we should call them Frankenstein’s ? Making these again very soon and I might add walnuts for an extra crunch!
My whole family loved these cookies! Perfect combination of our three favorite cookie add-ins. Thank you again for another awesome recipe. 🙂
So happy to hear that everyone loved the cookies, Elizabeth! These cookies are one of my favorites 🙂
Does old fashioned peanut butter that needs to be stirred work in these cookies? I’ve found that with some recipes you have to use the hydrogenated kind or the oil separates out
It doesn’t work as well as a brand like Jif or Skippy. I would suggest using one that doesn’t need to be stirred in these cookies.
These look delicious and worth trying! I look forward to baking these sometime soon I hope. Love how there’s so much positivity in your posts. There’s a lot of bloggers who exhibit judgmentalism and criticism on others choices, seemingly as a way of boosting the coolness or credibility of their posts but I find that very irksome (not to mention ethically questionable). You don’t do that – thank you! All the more reason I consider your blog to be number one. Kudos!
Thank you for the kind comment, Anna! I really do appreciate it! It means a lot that you consider my blog to be one of the top ones! 🙂